Gamba was fined and reprimanded by the league over the fans’ actions, Reuters reports, citing the local Kyodo news agency. The club later reportedly banned the fans involved. It has also imposed a full ban on flags and banners at home and away matches.

Gamba “immediately identified the supporter group in question and took swift and appropriate measures,” the BBC reported, citing a statement on the J-league website.

“However, the club’s efforts to establish a system of monitoring supporter activities and enlightening them is not enough to meet its important responsibility of preventing discriminatory action from happening,” the statement added.

The club currently sits third in Japan’s top league, with 19 points after 10 games played – two points behind league leaders Kashima Antlers.

At the end of April, Ukrainian team Dynamo Kiev fans took to the stadium wearing outfits of white supremacist group the Ku Klux Klan (KKK) and masks bearing swastikas during the visit of a UEFA inspector in their home match versus fierce rivals Shakhtar Donetsk.